Ball valve



FIG. 1 is a front perspective view of a ball valve showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a side elevational view thereof, the opposite side being the same as the side shown;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a ball valve, as shown and described. 